What is an interface?

I'm writing a paper at the moment on the cybernetics of organisational risk in hospitals. Most of my thinking about cybernetics has revolved around self-regulating functions in one form or another - most notably in things like Beer's Viable System Model, or Ashby's Homeostat. In doing this kind of analysis, we tend to draw diagrams with lines and boxes, rather like this:

Our focus is on the relations between the boxes (although attention is often drawn to the labels in the boxes). The practice of Beer's cybernetic management analysis involves identifying the components of an organisation which map onto the boxes in the diagram, and identifying the different levels of recursion at which those components operate. The valuable thing in this exercise is usually the conversation that emerges as stakeholders talk about their experience of the organisational situation. 

The problem is that modern organisations are so fluid, it is very hard to identify clearly which components are which: the boundaries between things are continually redrawn - being blurred, dissolved, shifted, etc. So looking at the diagram above again, what is interesting is not the lines connecting the boxes, or the boxes themselves - it is the lines around the boxes which are most important. 

For Beer (and Ashby), what occurs between an organism and its environment is transduction - the conversion of one set of signals, or a form of energy, into another. Beer's genius was to map the engineering concept of transduction onto social systems, pointing out that transduction in social systems must involve the management of complexity. Between an organism of complexity x, and an environment of complexity y, where y>x, the viability of the organism could be achieved through a combination of the attenuation of the environment by the organism, and the amplification of complexity within the organism. The transduction lies in this pattern of amplification and attenuation. 

But we shouldn't stop there. The transduction happens at the boundary. What actually happens in the boundary? 

This is a difficult question, but I'm increasingly aware of its importance. It is the same question as "What is an interface?". There is transduction between me and my computer screen now. There is transduction between my brain and my liver, or between a patient and the hospital admissions. But Beer's talk of amplification and attenuation, whilst useful because it maps on to ideas about technology "extending" the body (McLuhan), is less helpful when all our boundaries start to melt into some kind of Dali-esque confusion. 

What is clear is that there are differences in description on either side of the boundary. The patient's descriptions of the hospital are different from the hospital's description of the patient. The computer programmer's description of me is different from my description of the software. Every description contains a dynamic of constraints: the constraints bearing on the computer programmer are very different from the constraints I operate within when using their tools (the constraints which they created). So the transduction appears to do something to the descriptions...

But equally, this may be the wrong way of looking at it. Perhaps we see the boundary, and observe the transduction, because the boundary is an emergent phenomenon arising from two systems with different constraint dynamics. The transduction is a kind of knotted-nexus. Labelling the boundary and identifying the transduction merely codifies what is in reality a dynamic process. 

I find this a more useful way of thinking about it, because it retains the possibility that constraints on either side of the boundary might be reconfigured, and as a result every other distinction, and the boundary, might shift. We're seeing this happen a lot around us at the moment. Rather than talk about transductions and interfaces, we would be better getting to grips with the dynamics of interacting constraints.